text: #ifdef __cplusplus
  extern "C" {
  #endif
  
  #include "f2c.h"
  #include "hypre_lapack.h"
  
  /* Subroutine */ integer dsygst_(integer *itype,const char *uplo, integer *n, 
  	doublereal *a, integer *lda, doublereal *b, integer *ldb, integer *
  	info)
  {
  /*  -- LAPACK routine (version 3.0) --   
         Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
         Courant Institute, Argonne National Lab, and Rice University   
         September 30, 1994   
  
  
      Purpose   
      =======   
  
      DSYGST reduces a real symmetric-definite generalized eigenproblem   
      to standard form.   
  
      If ITYPE = 1, the problem is A*x = lambda*B*x,   
      and A is overwritten by inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T)   
  
      If ITYPE = 2 or 3, the problem is A*B*x = lambda*x or   
      B*A*x = lambda*x, and A is overwritten by U*A*U**T or L**T*A*L.   
  
      B must have been previously factorized as U**T*U or L*L**T by DPOTRF.   
  
      Arguments   
      =========   
  
      ITYPE   (input) INTEGER   
              = 1: compute inv(U**T)*A*inv(U) or inv(L)*A*inv(L**T);   
              = 2 or 3: compute U*A*U**T or L**T*A*L.   
  
      UPLO    (input) CHARACTER   
              = 'U':  Upper triangle of A is stored and B is factored as   
                      U**T*U;   
              = 'L':  Lower triangle of A is stored and B is factored as   
                      L*L**T.   
  
      N       (input) INTEGER   
              The order of the matrices A and B.  N >= 0.   
  
      A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)   
              On entry, the symmetric matrix A.  If UPLO = 'U', the leading   
              N-by-N upper triangular part of A contains the upper   
              triangular part of the matrix A, and the strictly lower   
              triangular part of A is not referenced.  If UPLO = 'L', the   
              leading N-by-N lower triangular part of A contains the lower   
              triangular part of the matrix A, and the strictly upper   
              triangular part of A is not referenced.   
  
              On exit, if INFO = 0, the transformed matrix, stored in the   
              same format as A.   
  
      LDA     (input) INTEGER   
              The leading dimension of the array A.  LDA >= max(1,N).   
  
      B       (input) DOUBLE PRECISION array, dimension (LDB,N)   
              The triangular factor from the Cholesky factorization of B,   
              as returned by DPOTRF.   
  
      LDB     (input) INTEGER   
              The leading dimension of the array B.  LDB >= max(1,N).   
  
      INFO    (output) INTEGER   
              = 0:  successful exit   
              < 0:  if INFO = -i, the i-th argument had an illegal value   
  
      =====================================================================   
  
  
         Test the input parameters.   
  
         Parameter adjustments */
      /* Table of constant values */
      static integer c__1 = 1;
      static integer c_n1 = -1;
      static doublereal c_b14 = 1.;
      static doublereal c_b16 = -.5;
      static doublereal c_b19 = -1.;
      static doublereal c_b52 = .5;
      
      /* System generated locals */
      integer a_dim1, a_offset, b_dim1, b_offset, i__1, i__2, i__3;
      /* Local variables */
      static integer k;
      extern logical lsame_(const char *,const char *);
      extern /* Subroutine */ integer dtrmm_(const char *,const char *,const char *,const char *, 
  	    integer *, integer *, doublereal *, doublereal *, integer *, 
  	    doublereal *, integer *), dsymm_(
  	    const char *,const char *, integer *, integer *, doublereal *, doublereal *, 
  	    integer *, doublereal *, integer *, doublereal *, doublereal *, 
  	    integer *);
      static logical upper;
      extern /* Subroutine */ integer dtrsm_(const char *,const char *,const char *,const char *, 
  	    integer *, integer *, doublereal *, doublereal *, integer *, 
  	    doublereal *, integer *), dsygs2_(
  	    integer *,const char *, integer *, doublereal *, integer *, doublereal 
  	    *, integer *, integer *);
      static integer kb;
      extern /* Subroutine */ integer dsyr2k_(const char *,const char *, integer *, integer *, 
  	    doublereal *, doublereal *, integer *, doublereal *, integer *, 
  	    doublereal *, doublereal *, integer *);
      static integer nb;
      extern /* Subroutine */ integer xerbla_(const char *, integer *);
      extern integer ilaenv_(integer *,const char *,const char *, integer *, integer *, 
  	    integer *, integer *, ftnlen, ftnlen);
  #define a_ref(a_1,a_2) a[(a_2)*a_dim1 + a_1]
  #define b_ref(a_1,a_2) b[(a_2)*b_dim1 + a_1]
  
  
      a_dim1 = *lda;
      a_offset = 1 + a_dim1 * 1;
      a -= a_offset;
      b_dim1 = *ldb;
      b_offset = 1 + b_dim1 * 1;
      b -= b_offset;
  
      /* Function Body */
      *info = 0;
      upper = lsame_(uplo, "U");
      if (*itype < 1 || *itype > 3) {
  	*info = -1;
      } else if (! upper && ! lsame_(uplo, "L")) {
  	*info = -2;
      } else if (*n < 0) {
  	*info = -3;
      } else if (*lda < max(1,*n)) {
  	*info = -5;
      } else if (*ldb < max(1,*n)) {
  	*info = -7;
      }
      if (*info != 0) {
  	i__1 = -(*info);
  	xerbla_("DSYGST", &i__1);
  	return 0;
      }
  
  /*     Quick return if possible */
  
      if (*n == 0) {
  	return 0;
      }
  
  /*     Determine the block size for this environment. */
  
      nb = ilaenv_(&c__1, "DSYGST", uplo, n, &c_n1, &c_n1, &c_n1, (ftnlen)6, (
  	    ftnlen)1);
  
      if (nb <= 1 || nb >= *n) {
  
  /*        Use unblocked code */
  
  	dsygs2_(itype, uplo, n, &a[a_offset], lda, &b[b_offset], ldb, info);
      } else {
  
  /*        Use blocked code */
  
  	if (*itype == 1) {
  	    if (upper) {
  
  /*              Compute inv(U')*A*inv(U) */
  
  		i__1 = *n;
  		i__2 = nb;
  		for (k = 1; i__2 < 0 ? k >= i__1 : k <= i__1; k += i__2) {
  /* Computing MIN */
  		    i__3 = *n - k + 1;
  		    kb = min(i__3,nb);
  
  /*                 Update the upper triangle of A(k:n,k:n) */
  
  		    dsygs2_(itype, uplo, &kb, &a_ref(k, k), lda, &b_ref(k, k),
  			     ldb, info);
  		    if (k + kb <= *n) {
  			i__3 = *n - k - kb + 1;
  			dtrsm_("Left", uplo, "Transpose", "Non-unit", &kb, &
  				i__3, &c_b14, &b_ref(k, k), ldb, &a_ref(k, k 
  				+ kb), lda);
  			i__3 = *n - k - kb + 1;
  			dsymm_("Left", uplo, &kb, &i__3, &c_b16, &a_ref(k, k),
  				 lda, &b_ref(k, k + kb), ldb, &c_b14, &a_ref(
  				k, k + kb), lda);
  			i__3 = *n - k - kb + 1;
  			dsyr2k_(uplo, "Transpose", &i__3, &kb, &c_b19, &a_ref(
  				k, k + kb), lda, &b_ref(k, k + kb), ldb, &
  				c_b14, &a_ref(k + kb, k + kb), lda);
  			i__3 = *n - k - kb + 1;
  			dsymm_("Left", uplo, &kb, &i__3, &c_b16, &a_ref(k, k),
  				 lda, &b_ref(k, k + kb), ldb, &c_b14, &a_ref(
  				k, k + kb), lda);
  			i__3 = *n - k - kb + 1;
  			dtrsm_("Right", uplo, "No transpose", "Non-unit", &kb,
  				 &i__3, &c_b14, &b_ref(k + kb, k + kb), ldb, &
  				a_ref(k, k + kb), lda);
  		    }
  /* L10: */
  		}
  	    } else {
  
  /*              Compute inv(L)*A*inv(L') */
  
  		i__2 = *n;
  		i__1 = nb;
  		for (k = 1; i__1 < 0 ? k >= i__2 : k <= i__2; k += i__1) {
  /* Computing MIN */
  		    i__3 = *n - k + 1;
  		    kb = min(i__3,nb);
  
  /*                 Update the lower triangle of A(k:n,k:n) */
  
  		    dsygs2_(itype, uplo, &kb, &a_ref(k, k), lda, &b_ref(k, k),
  			     ldb, info);
  		    if (k + kb <= *n) {
  			i__3 = *n - k - kb + 1;
  			dtrsm_("Right", uplo, "Transpose", "Non-unit", &i__3, 
  				&kb, &c_b14, &b_ref(k, k), ldb, &a_ref(k + kb,
  				 k), lda);
  			i__3 = *n - k - kb + 1;
  			dsymm_("Right", uplo, &i__3, &kb, &c_b16, &a_ref(k, k)
  				, lda, &b_ref(k + kb, k), ldb, &c_b14, &a_ref(
  				k + kb, k), lda);
  			i__3 = *n - k - kb + 1;
  			dsyr2k_(uplo, "No transpose", &i__3, &kb, &c_b19, &
  				a_ref(k + kb, k), lda, &b_ref(k + kb, k), ldb,
  				 &c_b14, &a_ref(k + kb, k + kb), lda);
  			i__3 = *n - k - kb + 1;
  			dsymm_("Right", uplo, &i__3, &kb, &c_b16, &a_ref(k, k)
  				, lda, &b_ref(k + kb, k), ldb, &c_b14, &a_ref(
  				k + kb, k), lda);
  			i__3 = *n - k - kb + 1;
  			dtrsm_("Left", uplo, "No transpose", "Non-unit", &
  				i__3, &kb, &c_b14, &b_ref(k + kb, k + kb), 
  				ldb, &a_ref(k + kb, k), lda);
  		    }
  /* L20: */
  		}
  	    }
  	} else {
  	    if (upper) {
  
  /*              Compute U*A*U' */
  
  		i__1 = *n;
  		i__2 = nb;
  		for (k = 1; i__2 < 0 ? k >= i__1 : k <= i__1; k += i__2) {
  /* Computing MIN */
  		    i__3 = *n - k + 1;
  		    kb = min(i__3,nb);
  
  /*                 Update the upper triangle of A(1:k+kb-1,1:k+kb-1) */
  
  		    i__3 = k - 1;
  		    dtrmm_("Left", uplo, "No transpose", "Non-unit", &i__3, &
  			    kb, &c_b14, &b[b_offset], ldb, &a_ref(1, k), lda);
  		    i__3 = k - 1;
  		    dsymm_("Right", uplo, &i__3, &kb, &c_b52, &a_ref(k, k), 
  			    lda, &b_ref(1, k), ldb, &c_b14, &a_ref(1, k), lda);
  		    i__3 = k - 1;
  		    dsyr2k_(uplo, "No transpose", &i__3, &kb, &c_b14, &a_ref(
  			    1, k), lda, &b_ref(1, k), ldb, &c_b14, &a[
  			    a_offset], lda);
  		    i__3 = k - 1;
  		    dsymm_("Right", uplo, &i__3, &kb, &c_b52, &a_ref(k, k), 
  			    lda, &b_ref(1, k), ldb, &c_b14, &a_ref(1, k), lda);
  		    i__3 = k - 1;
  		    dtrmm_("Right", uplo, "Transpose", "Non-unit", &i__3, &kb,
  			     &c_b14, &b_ref(k, k), ldb, &a_ref(1, k), lda);
  		    dsygs2_(itype, uplo, &kb, &a_ref(k, k), lda, &b_ref(k, k),
  			     ldb, info);
  /* L30: */
  		}
  	    } else {
  
  /*              Compute L'*A*L */
  
  		i__2 = *n;
  		i__1 = nb;
  		for (k = 1; i__1 < 0 ? k >= i__2 : k <= i__2; k += i__1) {
  /* Computing MIN */
  		    i__3 = *n - k + 1;
  		    kb = min(i__3,nb);
  
  /*                 Update the lower triangle of A(1:k+kb-1,1:k+kb-1) */
  
  		    i__3 = k - 1;
  		    dtrmm_("Right", uplo, "No transpose", "Non-unit", &kb, &
  			    i__3, &c_b14, &b[b_offset], ldb, &a_ref(k, 1), 
  			    lda);
  		    i__3 = k - 1;
  		    dsymm_("Left", uplo, &kb, &i__3, &c_b52, &a_ref(k, k), 
  			    lda, &b_ref(k, 1), ldb, &c_b14, &a_ref(k, 1), lda);
  		    i__3 = k - 1;
  		    dsyr2k_(uplo, "Transpose", &i__3, &kb, &c_b14, &a_ref(k, 
  			    1), lda, &b_ref(k, 1), ldb, &c_b14, &a[a_offset], 
  			    lda);
  		    i__3 = k - 1;
  		    dsymm_("Left", uplo, &kb, &i__3, &c_b52, &a_ref(k, k), 
  			    lda, &b_ref(k, 1), ldb, &c_b14, &a_ref(k, 1), lda);
  		    i__3 = k - 1;
  		    dtrmm_("Left", uplo, "Transpose", "Non-unit", &kb, &i__3, 
  			    &c_b14, &b_ref(k, k), ldb, &a_ref(k, 1), lda);
  		    dsygs2_(itype, uplo, &kb, &a_ref(k, k), lda, &b_ref(k, k),
  			     ldb, info);
  /* L40: */
  		}
  	    }
  	}
      }
      return 0;
  
  /*     End of DSYGST */
  
  } /* dsygst_ */
  
  #undef b_ref
  #undef a_ref
  
  #ifdef __cplusplus
  }
  #endif
  